A view of the world during daylight shows the world to be empty. Focus on a newspaper says that a German blood substitute failed. During night, the desolate city is shown to be alive and booming. This is the world of the vampires.

On a television two vampires are debating the current situation which has enveloped their society: a shortage of blood. A vagrant vampire snarls at a wealthy one and is quickly subdued by the police.

Edward Dalton (Ethan Hawke) drives to work at Bromley Marks Corp. He looks at his reflection in the mirror, but it isn’t there. He goes to a train station and waits for train. Underneath, two feral vampires, sub-siders, are fighting. They are winged monsters with no trace of human characteristics. Edward goes to work. He walks into a lab where humans are chained to harvesters for blood extraction. At a personnel meeting, a death sentenced prisoner was deprived of blood and the corporation knows that with the large blood shortage sub-siders will become more common. Since only 5% of the human population survived the outbreak to become vampires, Edward realizes that the corporation he works for has actively discovered what will be the extinction of the human race in it’s recognizable form. Charles Bromley (Sam Neill) listens intently and then calls Edward to meet in private.

Charles and Edward have blood coffee in private. Charles tells Edward that in 2008 he contracted cancer and was then forced to tell his daughter, Alison, that he was dying. She was devastated and Charles prayed for a miracle. He then became a vampire and immortal and was happy. But Alison saw vampirism as a disease and she ran from Charles, rejecting the life of vampirism. Charles notices that Edward doesn’t drink his coffee and asks if he pities the humans. Charles wants Edward to test a blood substitute in order to save the human race.

Edward’s lab partner was testing on the substitute on animals, and tells Edward that it works. It’s time for testing on vampires. Unfortunately, the situation in the outside world is deteriorating. The need for blood has driven society to crime and it’s only getting worse. They test the substitute on a vampire patient. His temperature increases quickly and then stabilizes as the substitute is added. He then starts vomiting as boils appear all over his body. The Vampire convulses and the boil disappears before he explodes. Edward looks on in grave horror.

He drives home while listening to the news. He is able to see his ear in the mirror for a moment, which shocks him. He hits another car and the two spin off and crash. He goes over to the other car and the driver shoots him through the wrist with a crossbow. He realizes that they are human. Once sirens appear, he hastily tells them to get in his car. He puts the daytime protection mode on his car so that the police can’t look inside. He directs the police to the opposite direction and then the humans get out of his car. They thank him and he asks if they are ok. They leave and wish him a happy birthday.

Back at Bromley Marks Corp’s residential area, Edward enters his apartment and listens to advertisements. Vampires travel through the city via the SubWalk system. His door opens and his friend Frank visits. He has been gone for months and gives his brother a bottle of human blood as a birthday present. It’s his 10th 35th Birthday. Edward doesn’t want to drink the blood and Frank gets upset. Frank hunts humans for their government. Edward tells Frank that the substitute will mean the end of human hunting. He pours the blood down the sink and Frank throws the bloodless bottle against the wall. A feral vampire enters the house to lick the blood and the brothers are shocked. Frank tries to attack it but the vampire just starts drinking before throwing Frankie away. Edward fights the feral vampire with a chair while protecting his brother. The two attempt to stake it with a kitchen knife. Frankie decapitates it and the two brothers call the police.

The Police tell Edward to update his security. The forensics officer cuts off the ring finger of the subsider’s corpse and sees a wedding ring. “Together forever  Lily and Carl.” Edward tells the police he knew Carl, a gardener, and had seen him two weeks prior. Carl had hit hard times and started feeding on himself, which turned him into a sub-sider.

During the day, Edward’s backdoor opens and his security system tells him that someone has entered the premises. He cautiously walks around and turns on the light to see the female leader of the humans, Audrey, pointing a crossbow at his heart. Audrey tells him that there is a cure for vampirism and gives him a map to a meeting place. She then leaves since she knows she can trust him. He walks upstairs and sees Frankie was listening. Frankie looks conflicted but doesn’t press the matter.

Bromley Marks is encountering public backlash for not being able to handle the blood shortage. Edward visits and asks Charles if the blood substitute would put a permanent end to human hunting. Charles says that there will be time for the human race to repopulate and tells him that there will always be people who want to pay more for “the real thing.” Edward asks how Charles would feel about someone hunting Alice.

During the day, at noon, Edward drives over to the meeting area and stops his car in front of Audrey. She tells him that “He” is waiting for Edward. Edward drives to the tree and puts on a hat and glasses before debating whether to step outside. He steps out into the shade and avoids the sunlight so that he doesn’t burst into flames. He sees another car and approaches it cautiously. He meets “Elvis” (Willem Dafoe) sitting under the tree. Elvis is carrying a crossbow and they discuss their common interest: a future for the human race.

As the two talk, Frankie, who is covered in black riot gear, attacks Aubrey. Elvis tells Edward that he was a vampire once…but not anymore. He shows Edward his bite marks and then makes Edward feel his beating heart. Aubrey is then marched out and a stand off ensues between Edward, Elvis and Frankie. Frankie is distracted by the sound of his reinforcements and Aubrey knocks him out. The trio pile into Edward’s car and drive away with reinforcements in pursuit, firing bullet’s into the car. Elvis takes over and drives through a hole in the windshield while they keep Edward away from the rays of light. As more and more armored vans appear, Elvis takes a gamble and drives over a destroyed bridge. The tanks follow, only to crash and explode.

Elvis is pissed that his car got destroyed and drives the trio to a hideout in the desert. He then explains that he was never good with science but tells him how he discovered the cure for vampirism. He was driving during the daylight for the thrill of it and ended up crashing due to lack of blood. He lost control and crashed. He was thrown out of the car and exposed to daylight, which set him on fire. He then fell into the water and was dowsed with water. When he surfaced, he was burned but cured thanks to the sunlight. Edward is skeptical, but Elvis insists that it is true.

At Bromley Marks, Charles calls Frankie in for a meeting. He introduces himself and congratulates Frankie for reporting his brother. Charles requests that Frankie hunt down and turn his daughter Alice (Isabel Lucas) into a vampire so that he can be with her forever.

Aubrey asks Edward about the last time he fed since she noticed that Edward was distracted and out of focus. She cuts her hand a pours blood into a cup and forces him to drink it. They arrive at the human shelter and Edward isn’t very comfortable. It becomes clear that Edward wants to become human again as he admires the human shelter and it’s inhabitants. They are in the cellar of an old vineyard. Elvis brings Edward to a vampire politician who wants to rebuild the human race. They want to bring humans back in a big way, but know that Charles would exploit the cure to farm more humans.

As the price of blood increases, the vampires become more and more desperate for blood. Vampires can only get 5% blood in coffee. A man tries to steal some and they attack the blood stand. Policemen arrive and attack the rioters until they are all subdued.

Edward asks Elvis about how it felt to transform. Elvis tells him that the sunlight deep fried him and electrocuted his heart into restarting. Edward realizes that if blood is separated and exposed, nothing happens. The body can only transform back to human form if exposed in a specific manner. Edward and Aubrey talk about his condition and Edward tells her that he forgets what it is like to be human. He tells her that a part of him is afraid to die. Frankie betrayed Edward and turned him into a vampire. He then sees a fermentation tank and realizes that it is air tight. Using the tank, he can create a control burn which will keep vampires from burning to a crisp.

Alison and a human driver called Jarvis drive toward the vineyard with a large amount of humans in caravans. Their tires pop and the caravan is forced to stop. They turn on their UV lights and draw guns. Vampire Hunters start shooting tranquilizer darts at all of the humans until they are all incapacitated. Jarvis gets one in the hart with an arrow and the vampires explode upon staking. However, after a little while, all the humans have been knocked out. Alison sends out a distress call before they tranquillize her. Frankie activates a trace on the radio. The vampire Senator gives the humans a new place to hide, but Edward is intent upon testing the experiment to see if he can become human. Elvis decides to stay behind with Edward.

At Bromley Marks, Alice comes to in the lab. Charles arrives and talks to her. She begs for her friends’ safety. Charles tells her that she is so beautiful and grew up so much. He hugs her and tells her that she’s safe but that it is too late for her friends. He asks her to join him before realizing that she stabbed him in the gut. She tries to take the elevator but Frankie knocks her out.

As it draws closer to Noon, Edward prepares to test the fermentation vat and become human. Aubrey touches him and he tells her that she feels warm. As he prepares the fermentation vat, tanks approach the vineyard ready to capture the trio. Elvis opens the tank and Edward bursts into flames. The fire goes out when the tank becomes airtight. Edward heals but isn’t cure. They try again, testing his heartbeat with an EKG monitor (heartbeat shows it’s working). Edward exposes himself completely and revives as a human. The Vampire hunters arrive soon after but do not find the trio.

Frankie and Charles talk with one another. He sends Frankie to Alison and he turns her into a vampire after telling her that being a vampire is true freedom. He feeds on her then leaves her to turn on the ground.

Edward walks out into the daylight for the first time in ten years. Elvis gets his car from the garage and it becomes clear that the group intend to go to the Senator’s. They drive to his cabin only to find everyone has been rounded up or killed and the Senator has been staked. Edward tells Aubrey that he can save them and decides to bring them to his lab partner, Chris.

Charles visits Alice, who refuses to drink her blood ratios. Instead she feeds on herself. She tries to force him to drink her blood, but Charles refuses in disgust. She is slowly losing her grip on humanity and begins to turn into a sub-sider.

As the blood thins, the issue becomes not the trouble in finding blood, but the rise of the subsiders. Vampire policemen try to round up and imprison the people who can become subsiders. The imprisoned are shown half transformed and being rounded up like slaves. The untransformed vampires are disgusted and afraid that they will soon all become like the sub-siders. The sub-siders are thrown into the sun and burned to a crisp. Without a reprieve from sunlight they turn to dust. Alison melts away to nothing as the vampires look on. Frankie becomes disillusioned with this lifestyle and decides to help his brother.

Chris discovers a blood substitute and goes home to celebrate. He arrives and sees Edward, Elvis and Aubrey in his living room. He realizes that Edward is human and shocked. Edward tells him that what they have is a chance to change everything back to the way it was. Chris is shocked by this and asks how Edward was cured. Edward is about to answer when the phone rings. Chris doesn’t pick up immediately but does upon Elvis’s prompting. He claims it’s his ex-wife and goes into another room. Instead of wanting a cure, Chris wants his substitute to be the salvation of the future. Vampires storm the building and capture Aubrey. Edward and Elvis fight back and escape through a backdoor. They enter the SubWalk and end up followed by Frankie, who saves them from a sub-sider.

Frankie tells Edward that when he turned him, he did so to save his life since he knew the humans would be hunted for food. Frankie wants to help Edward, but his need for blood drives him to feed on Elvis. However, once he does, he changes back to human form. Edward was shocked that the blood turned Frankie back and realizes that it “cured” blood turns vampires human as well.

Edward returns to Bromley Marks and sets off all of their sensors in his attempt to get to Aubrey. She is captive in a chair with Charles, bleeding from her wrists to fill his cup. Edward is brought in forced to listen to Charles. He tells Charles that he doesn’t want to die. He claims that he never realized that being a vampire was the key to living forever. He tells Charles that he needs to turn him and Aubrey in order for Edward to give him the method of turning back to human. Charles tells him that they don’t need the cure thanks to Chris’s blood substitute.

Charles calls Edward a weak coward and then Edward calls Charles out on having Frankie turn Alison. This upsets Charles enough in forcing him to feed. It cures Charles and he instantly realizes that something is wrong. He collapses in front of Edward and asks what has happened. As Charles transforms, Edward breaks a chair and blocks the door so that transformation cannot be stopped. Edward welcomes him back to humanity and tells him that now, Charles is going to die. Charles is sent out, gagged and bloody, and his troops feed on him. All the guards become human and are then fed upon by other vampires. Frankie drives Elvis’s car into the building and saves his brother and Aubrey. However, Frankie is surrounded by guards. He begs them not to attack since there is a cure. He offers himself to the horde and they feed on him until he is dead and they are all cured.

A guard grabs Aubrey and Edward stakes him to save Aubrey. He grabs her and the two leave the building. A mass feeding frenzy hits the city and the cure rapidly spreads. With a cure now running rampantly through the city and the streets running red with that cure, Edward and Aubrey leave the building. Only three human guards remain alive at the end of the frenzy. Chris arrives and kills them since he doesn’t want the cure to spread. However, Elvis arrives and stakes Chris. Edward mourns Frankie but now has a strengthened resolve to spread the cure.

As dawn arrives, the trio leaves the building in Elvis’s car ready to cure everyone in the world of the disease.